Lecture 15: Arthropods 2 Flashcards
Groups of Myriaapods
- Chilopoda (centipedes- one pair of appendages/segment)
2. Diplopoda (milipedes- two pairs of appendages/segments)
Centipedes
carnivorous
300 sp
Milipedes
herbivore, derivores
11,000 sp
Three groups of Chelicerates
- Merostomata: horseshoe crabs
- Pycngoids: sea spiders
- Arachnids: spiders, scorpions, pseudoscorbians etc.
Crustaceans
- Isopods (wood lice)
- Theocostraca (barnacles)
- Decapods (shrimps, lobsters, cray fish)
- Cladocerans (water fleas)
Cephalothorax
antenna + peripods (actual limbs)
Abdomen
pleopods (used for swimming), uropods and telson
insects respiratory system
air sacs on exoskeleton to allow for respiration with trachea and spicules
decapods respiratory system
have gills
spiders + scorpions respiratory system
have book lungs and lamellae surrounded by muscles
spider circulatory system
ventral portion of abdomen
insect circulatory system
multiple hearts
body plan of insects
head, thorax, abdomen
evolutionary success of insects include
- diversity of mouthparts for different feeding types
- ability to fly
- new mechanism for delivering oxygen into internal tissues
Hormones
chemical messengers secreted by endocrine cells
distributed by blood
How to hormones work?
affect expression of gene
alter activity of enzyme
change permeability of membrane
autocrine signals
act on same cell that secretes hormone
paracrine signals
diffuse locally and work on neighbouring cells
endocrine signals
carried between cells by blood and other fluids
PTTH
hormone that is released by prothoracic gland in brain
ecdysone
signals moulting in insects
released by PTTH
maintains insect in larvel stages unless PTTH is present
